The study of patterns of inheritance and variations in organisms

GENETICS

the study of patterns of inheritance and variations in organisms.

GENES: control each trait of living thing by controlling the FORMATION of an organisms PROTEINS.

GENETICS

Chromosomes are DIPLOID (A PAIR OF CHROMOSOMES) therefore, each cell contains TWO GENES for each TRAIT.▪One from MOM▪One from DAD

GENETICS

Genes may be the SAME or they could be DIFFERENT▪Produce DIFFERENT CHARACTERISTICS of each TRAIT▪EXAMPLE: gene for plant height might occur in TALL or SHORT form.

GENETICS

▪Different forms of a gene are called ALLELES▪The TWO ALLELES are SEGREGATED during GAMETE FORMATION (MEIOSIS II)

GENETICS

▪Dominant allele: allele that is EXPRESSED

▪Recessive allele: allele that is ONLY EXPRESSED when there is no dominant allele present.

GENETICS

Modern Genetics: Based on GREGOR MENDEL’S explanations for the patterns of HEREDITY in garden PEA PLANTS.

Mendel’s Breeding Experiments

▪CROSSING different PEA PLANTS▪Crossing: to mate or BREED two INDIVIDUALSPea plant with PURPLE FLOWERS with a type that has WHITE FLOWERS.ALL OFFSPRING HAD PURPLE FLOWERS


Mendel CROSSED those OFFSPRING and produced some WHITE FLOWERS and some PURPLE FLOWERS.

(THE WHITE FLOWERS CAME BACK!)


Mendel realized that these results were explainable if three things were true. He hypothesized that:

Mendel experiment:

1. Every trait (like flower color, or seed shape, or seed color) is controlled by two "heritable factors". [We know now that these are genes - we each have two copies of every gene].

2. If the two alleles differ, one is dominant and one is recessive. Dominant traits mask the appearance of recessive traits.

Mendel experiment:

3. Alleles are randomly donated from parents to offspring - the factors (alleles) separate when the gametes are formed by meiosis, allowing all possible combinations of factors to occur in the gametes.

Mendel experiment:

3. Gene Composition is known as GENOTYPE The expression of the genes is PHENOTYPE

EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES

Gene compositiona.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES

▪It’s was you SEE


b. two paired ALLELES in an organism’s genotype may be IDENTICAL, HOMOZYGOUS.


c. The two paired ALLELES in an organism can also be DIFFERENT, HETEROZYGOUS. ▪DOMINANT trait is EXPRESSED


Mendel’s Law of DOMINANCE: When an organism has TWO DIFFERENT ALLELES for a trait, ONE ALLELE IS DOMINANT.

Mendels Laws of Genetics

a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES

Mendel’s Law of SEGREGATION: During GAMETE formation by a DIPLOID organism, the pair of ALLELES for a trait SEPARATE, during MEIOSIS.


a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES

Mendel’s Law of INDEPENDENT ASSORTMENT: The members of a GENE PAIR SEPARATE from one another INDEPENDENTLY from the members of the other GENE PAIRs.



NAME MENDELS 3 LAWS OF GENETICS

1.2.3.

PUNNETT SQUARE

5. Using a PUNNETT SQUARE: to PREDICT the PROBABLE GENETIC COMBINATIONS in the OFFSPRING that result from different PARENTAL ALLELE COBINATIONS that are INDEPENDENTLY assorted.

MONOHYBRID CROSS examines the inheritance of ONE TRAIT.▪HOMOZYGOUS-HOMOZYGOUS

PUNNETT SQUARE

▪HETEROZYGOUS-HETEROZYGOUS

PUNNETT SQUARE

▪HETEROZYGOUS-HOMOZYGOUS

PUNNETT SQUARE

▪HETEROZYGOUS-HOMOZYGOUS

PUNNETT SQUARE

EXAMPLE: trait for height▪ T= DOMINANT TALL▪ t= RECESSIVE SHORT

The suare shows the following GENOTYPES:

PARENTS ARE THE F1 GENERATION resulting in offspring as F2 GENERATION

PUNNETT SQUARE

PUNNETT SQUARE

The square shows the following GENOTYPES:

1:4 RATIO of__________________ ____%

1:4 RATIO of__________________ ____%

2:4 RATIO of__________________ ____%

PUNNETT SQUARE

The square shows the following PHENOTYPES:

3:4 RATIO of__________________ ____%

1:4 RATIO of__________________ ____%

USING A PEDIGREE

a PEDIGREE is a family history that shows HOW A TRAIT is INHERITED over several GENERATIONS.

a. can help answer questions about THREE aspects of inheritance

1. SEX LINKAGE2. DOMINANCE3.

HETEROZYGOSITY

7. SEX LINKAGE: a gene located on either the X or the Y chromosome.

a. females have TWO X CHROMOSOMES

1. The Y CHROMOSOME is SHORTER than the x chromosome. Therefore, it CANNOT HOLD AS MANY TRAITS.

b. males have ONE X AND ONE Y CHROMOSOME.

8. Genetic Engineering:

PROCESS OF REPLACING SPECIFIC GENES IN AN ORGANISM IN ORDER TO ENSURE THAT THE ORGANISM EXPRESSES A DESIRED TRAIT.

8. Genetic Engineering:

a. Take specific genes from ONE ORGANISM and place them INTO ANOTHER ORGANISM.

1. CLONING: an IDENTICAL copy of a gene or an entire organism is produced.

1. CLONING: an IDENTICAL copy of a gene or an entire organism is produced.

2. Gene Therapy:

scientists INSERT a normal gene into an ABSENT OR ABNORMAL GENE. Once inserted the normal gene begins to produce CORRECT proteins or enzymes. This ELIMINATES the cause of the disorder

3. Results of genetic engineering may include:

a. the development of PLANTS that make their own INSECTICIDES.

b. the development of ANIMALS that are BIGGER, FASTER, RESISTANT TO DISEASE.

9. SELECTIVE BREEDING: method of artificially SELECTING and BREEDING only organisms with a DESIRED TRAIT to produce the next generation.

a. inbreeding: CROSSING INDIVIDUALS THAT ARE CLOSELY RELATED.

1. NOT THE BEST OPTION: DISEASE DEVELOPS EASILY.

b. HYBRIDIZATION: choosing and breeding organisms that show STRONG EXPRESSION for TWO DIFFERENT TRAITS in order to produce their offspring that express the desired traits.

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The study of patterns of inheritance and variations in organisms